Comparative studies of the tribological behaviors and tribo-chemical mechanisms for AlMgB14-TiB2 coatings and B4C coatings lubricated with molybdenum dialkyl-dithiocarbamate

We compared the tribological behaviors and the tribo-chemical mechanisms of AlMgB14-TiB2 coatings and B4C coatings under lubrication with molybdenum dialkyl-dithiocarbamate (MoDTC). In unidirectional sliding contact, the boride coatings exhibited an unstable tribological performance, while the friction coefficients of these coatings maintained a very steady low level in reciprocating sliding contact. No severe wear occurred to the boride coatings. However, significant abrasive wear was observed on the steel balls rubbing against the boride coatings under unidirectional sliding contact. Analysis indicated incomplete dissociation of MoDTC at coating wear tracks and no formation of MoS2 tribofilms on steel counterfaces in the case of unidirectional sliding contact, whereas well-developed MoS2 tribofilms were formed on AlMgB14-TiB2 coatings under reciprocating sliding condition.